fix mailing list address, the nabble link should be reactivate

git-svn-id: http://svn.zoo-project.org/svn/trunk@397 4b6b6ad6-68b3-4dcc-9231-bd9b83bc5dc3
add debug page to documentation

git-svn-id: http://svn.zoo-project.org/svn/trunk@398 4b6b6ad6-68b3-4dcc-9231-bd9b83bc5dc3
move information about return code

git-svn-id: http://svn.zoo-project.org/svn/trunk@399 4b6b6ad6-68b3-4dcc-9231-bd9b83bc5dc3